“Surface retarders” are compositions used for treating the surface of concrete compositions. Fresh concrete containing aggregates is poured and leveled, and then the surface retarder is sprayed onto the surface at a rate of approximately 200 g/m2. After a number of hours, the treated surface is washed off with a jet of water under high pressure to remove uncured cement and to expose the aggregates on the surface.
At present, surface retarders have been water-based or solvent-based. In other words, the retarding agent “actives” (e.g., sucrose, organic acids or their salts, etc.) are either dissolved in water or suspended in a solvent.
Water-based and solvent-based surface retarders, however, have respective advantages and disadvantages. For example, the solvent-based ones, which are derived from petroleum distillates, are typically less sensitive to the effects of rain and sun, but are not favored from an environmentalist's viewpoint. The water-based surface retarders, while environmentally friendly, suffer in terms of performance when exposed to high heat or sunlight, because they are susceptible to evaporation.
Accordingly, novel surface retarders are needed in view of these respective disadvantages.